Nonaqueous electrolyte secondary batteries such as a lithium secondary battery are currently in wide use as (i) batteries for devices such as a personal computer, a mobile telephone, and a portable information terminal or (ii) on-vehicle batteries.
An example of a separator known to be used for such a nonaqueous electrolyte secondary battery is a laminated separator in which a porous layer containing a filler and a resin is disposed on at least one surface of a porous base material containing polyolefin as a main component.
For example, Patent Literature 1 discloses a nonaqueous secondary battery laminated separator in which a heat-resistant porous layer containing a filler and also containing an aramid resin as a main component is disposed on at least one surface of a porous base material. Meanwhile, Patent Literature 2 discloses a nonaqueous secondary battery laminated separator in which a heat-resistant porous layer containing a water-soluble polymer as a binder and also containing a filler as a main component is disposed on at least one surface of a porous base material.
During assembly of a nonaqueous electrolyte secondary battery, an electrode and a separator are press-bonded through a press in order to increase adhesion between the electrode and the separator. A separator, typified by the separator disclosed in Patent Literature 1, in which a porous layer containing a resin as a main component is laminated has high adhesion, but has a drawback of not having a sufficiently high battery characteristic due to its low air permeability. Meanwhile, a separator, typified by the separator disclosed in Patent Literature 2, in which a porous layer containing a filler as a main component is laminated has high air permeability, but has no adhesion to an electrode. This causes misalignment between the electrode and the separator occurs during assembly of a battery and thus deteriorates a battery characteristic.